Recently, vehicles are manufactured based on studies conducted to secure driving force using internal combustion engines and/or electric motors, in order to reduce air pollution from exhaust gas of vehicles. Accordingly, the vehicles have evolved in the order of hybrid vehicles, plug-in hybrid vehicles and electric vehicles. In this case, the hybrid vehicles and plug-in hybrid vehicles have an internal combustion engine, an electric motor and a battery pack, and the electric vehicles have an electric motor and a battery pack, but not an internal combustion engine.
Accordingly, the battery pack has evolved together with hybrid vehicles, plug-in hybrid vehicles and electric vehicles. The battery pack is configured to be chargeable from outside an electric vehicle. The battery pack has a pack case and a battery module, and the pack case comprises an upper case and a lower case, thereby encasing the battery module. The battery module has battery cells and cartridges. The cartridge is configured to accommodate one or more battery cells. Here, the battery module is configured to physically secure the cartridges into one component.
The battery module is encased by the lower case and the upper case, and is transported using a handle that is fixated to the upper case or detachably attached to the upper case. When the handle is fixated to the upper case, the handle is applied with external force intermittently or repeatedly through the pack case during the life expectancy of use of the battery pack, thereby generating crack in a contact portion of the upper case due to stress. The crack introduces foreign substance from outside towards inside the pack case. The foreign substance induces electrical short-circuit of the battery module.
When the handle is detachably coupled to the upper case, the handle is coupled to the upper case only in one direction on the upper case, and thus, during transportation of the battery pack, the handle is separated from the upper case due to severe shaking of the lower and upper cases, or due to excessive bending of the handle from the lower and upper cases due to the transporting posture of a transporting person. Separation of the handle from the upper case induces crushing of the lower case through collision of a peripheral structure and the pack case, and indirectly impacts the battery module through the crushing of the lower case.
The impact on the battery module keeps the battery module from maintaining the electrical property that it initially intended. Therefore, numerous studies are being conducted to prevent the introduction of foreign substance from outside towards inside the pack case and to prevent the crushing of the lower case. One example of the studies mentioned above is disclosed in ‘Battery Pack’ of Japanese Patent Publication No. 2010-251127 (laid-open on Nov. 4, 2010). The battery pack has battery holders, portable handles and cases. The battery holders accommodate batteries that are stacked sequentially.
The portable handle is formed in a bow shape, and has connecting shafts and flanges at both ends. The connecting shaft protrudes from the end towards the inside of the bow. The flange protrudes from the end towards the outside of the bow such that it corresponds to the connecting shaft. The cases accommodates the battery holders in a central region, and is coupled to the portable handle at an upper side to be screw-coupled through an edge. Here, after the screw-coupling of the cases, the portable handle rotates relatively with respect to the cases through space between the cases at the upper side.
However, since the cases must be screw-coupled so that the portable handle is mounted onto the cases, the assembly process of the portable handle and the cases is very complicated, thereby increasing the manufacturing cost per unit of the battery pack.